Process for producing a ceramic body

ABSTRACT

A process for preparing a ceramic body in which a ceramic mixture is formed into a green body and thereafter fired. The ceramic mixture is prepared by mixing at least about 40 weight percent of ceramic material and less than about 60 weight percent of gluten with water. At least about 90 weight percent of the particles of ceramic material are smaller than about 20 microns, and at least about 50 weight percent of the particles of ceramic material are from about 0.5 to about 2 microns. The mixture has a pH of from about 2 to about 8.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This is a continuation-in-part of applicants' patent application U.S.Ser. No. 08/156,359, filed Nov. 23, 1993, now U.S. Pat. No. 5,458,837,which is a continuation-in-part of applicants' patent application Ser.No. 07/936,762, filed Aug. 27, 1992, now U.S. Pat. No. 5,298,205.

FIELD OF THE INVENTION

A process for making a ceramic filter body from a batch containing anorganic material and ceramic material is disclosed.

BACKGROUND OF THE INVENTION

Processes are known for making shaped ceramic materials using naturalobjects as a mold. However, when such processes are used to attempt tomake complicated shapes, many problems often arise. In the first place,because of the high shrinkage of most ceramic materials, cracking of theceramic body often occurs upon drying the green body and/or upon firingit. In the second place, inasmuch as moisture often is present in thepores of the green body, the evaporation of this moisture during dryingor firing often causes cracking of the body.

It is an object of this invention to provide a ceramic batch materialwhich is uniquely suitable for forming complicated shapes.

It is another object of this invention to provide a ceramic batchmaterial which will expand during thermal processing and will assume theshape of a mold in which it is situated.

It is another object of this invention to provide an intermediatematerial which is comprised of the ceramic batch material and which canbe used to form a fired, shaped body.

It is another object of this invention to provide a process forpreparing a ceramic body with a unique pore size and distribution whichis suitable for use as a ceramic filter.

It is yet another object of this invention to provide a process forpreparing a ceramic wick.

SUMMARY OF THE INVENTION

In accordance with this invention, there is provided a process formaking a ceramic filter body. In the first step of this process, acomposition comprised of organic material (such as gluten) and ceramicmaterial is provided. Thereafter, the composition is formed into a greenbody and fired.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood by reference to thefollowing detailed description thereof, when read in conjunction withthe attached drawings, wherein like reference numerals refer to likeelements, and wherein:

FIG. 1 is a flow diagram illustrating several preferred processes ofapplicants' invention;

FIG. 2 is a flow diagram illustrating one preferred coating process ofthe invention;

FIG. 3 is a flow diagram illustrating one preferred baking process ofthe invention;

FIG. 4 is a flow diagram illustrating one preferred forming process ofthe invention;

FIGS. 5, 6, 7, and 8, are views illustrating a ceramic wick comprised ofone of the compositions of this invention as well as the use of suchwick;

FIG. 9 illustrates a burner assembly which may be produced by theprocess of this invention;

FIG. 10 illustrates a particular ceramic body made from the compositionof this invention;

FIG. 11 illustrates the use of plant growing media made from one of thepreferred compositions of this invention;

FIG. 12 illustrates a filter made from one of the compositions of theinvention;

FIG. 13 is a sectional view of a seed capsule made from one of thecompositions of the invention;

FIGS. 14, 15, and 16 illustrate the use of the composition of theinvention as a plant growing medium;

FIG. 17 illustrates a porous ceramic material made by a preferredprocess of the invention which may be infiltrated by polymeric material;

FIG. 18 illustrates a porous tile made by one preferred process of theinvention;

FIG. 19 illustrates a cermet material made by one preferred process ofthe invention;

FIG. 20 illustrates a battery made by one preferred process of theinvention;

FIG. 21 illustrates a bone patch material made by a preferred process ofthe invention;

FIG. 22 illustrates a waste disposal core made by a preferred process ofthe invention;

FIG. 23 is a sectional view of a burner core which may be made by theprocess of this invention;

FIG. 24 is a sectional view of one ceramic body made by the process ofthis invention;

FIGS. 25 and 26 illustrate other forming processes;

FIG. 27 is a flow diagram of a process for producing a filter body witha substantial effective porosity;

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention involves the discovery that a ceramic compositioncomprised of at least 10 weight percent of ceramic material and aneffective amount of an organic material (such as gluten) is asurprisingly effective product. The preferred organic material isgluten, and gluten will be referred to in the remainder of thisspecification.

The ceramic composition of this invention is preferably comprised of atleast about 0.1 weight percent of gluten, by combined weight of ceramicmaterial and gluten. As is known to those skilled in the art, manymaterials contain both gluten and other organic materials; thus, cornmeal contains both corn gluten, fiber, fat, and other materials. When,for example, the concentration of ceramic material in a mixturecomprised of corn meal is to be calculated, one first determines theconcentration of the corn gluten in the corn meal.

As is known to those skilled in the art, gluten is comprised of at least85 weight percent of protein. The proteins in gluten include gliadin,glutenin, globulin, and albumin.

Gliadin is a prolamin (a simple vegetable protein) which is described,e.g., in U.S. Pat. Nos. 4,935,257 and 4,911,942, the disclosure of eachof which is hereby incorporated by reference into this specification.Wheat gliadin contains about 52.7 percent of carbon, about 17.7 percentof nitrogen, about 21.7 percent of oxygen, about 6.9 percent ofhydrogen, and about 1.0 percent of sulfur; and it is composed of 18amino acids, about 40 weight percent being glutamic acid.

Glutenin is one of the proteins present in wheat flour in substantialpercentage; it is composed of 18 amino acids. Glutenin is described inU.S. Pat. Nos. 3,651,768, 4,911,942, and 4,935,257, the disclosure ofeach of which is hereby incorporated by reference into thisspecification.

Globulin is a general name for a member of a heterogeneous group ofserum proteins precipitated by 50 percent saturated ammonium sulfate,and thus differing from albumin, the protein present in greatestconcentration in normal serum. Globulin generally may be coagulated byheat, is insoluble in water, and is soluble in dilute solutions ofsalts, strong acids, and strong alkalies. Globulin is described, e.g.,in U.S. Pat. Nos. 4,670,544, 4,482,483, and 3,985,506, the disclosure ofeach of which is hereby incorporated by reference into thisspecification.

Albumin is a widely-occurring water-soluble protein which can be readilycoagulated by heat and hydrolyzes to alpha-amino acids or theirderivatives. Albumin is described, e.g., in U.S. Pat. Nos. 5,055,407,5,053,490, 5,051,406, and 5,000,974, the disclosure of each of which ishereby incorporated by reference into this specification.

In one preferred embodiment, the gluten used in this invention containsat least about 89 weight percent of protein, at least 7 weight percentof lipids, and at least 2.0 weight percent of carbohydrates.

Gluten is described in many United States patents. Thus, by way ofillustration and not limitation, gluten is described in U.S. Pat. Nos.5,030,268 (corn gluten meal), 5,013,561 (gluten from waxy barley),5,004,624 (vital wheat gluten), 4,990,173 (corn gluten meal), 4,961,937(high gluten wheat flour), 4,960,705 (thickened corn gluten), 4,953,401(gluten in wheat), 4,950,496, 4,946,699, 4,942,043 (corn gluten meal),4,938,976 (wheat gluten of high viscous texture), 4,913,917, 4,911,939,4,879,133, 4,871,577, 4,861,482, 4,849,239 (PL gluten), 4,826,765,4,818,557, 4,764,199 (corn gluten meal), and the like. The disclosure ofeach of these patents is hereby incorporated by reference into thisspecification. As will be apparent to those skilled in the art, many ofthe gluten materials described above, which may be used in applicants'process, are mixtures of two or more different types of gluten and/orother materials.

In one preferred embodiment, the gluten material used in the process hasa particle size distribution, as measured when the gluten is dry(containing less than about 0.1 weight percent of moisture) such thatsubstantially all of the gluten particles are smaller than about 150microns and, more preferably, are smaller than about 40 microns.

As is well known to those skilled in the art, gluten is a commerciallyavailable product which is readily available. Thus, e.g., by way ofillustration, one may purchase "vital wheat gluten" from the ZieglersCompany of 6890 Kinne Street, East Syracuse, N.Y. as catalog number058030. Thus, by way of further illustration, one may purchase highgluten flour as either product N4117 or N4146 from the Keck's Meat andFood Service Company of Millerton, Pa.

In the process of this invention, a mixture of gluten and ceramicmaterial is used. It is preferred that at least 40 weight percent ofceramic material (by combined dry weight of gluten less than 0.1 weightpercent of moisture! and ceramic material) be used in the mixture. It ismore preferred that at least about 60 weight percent of said mixture ofgluten and ceramic material (by dry weight) be comprised of the ceramicmaterial. In an even more preferred embodiment, at least 75 weightpercent of ceramic material (by dry weight of ceramic material andgluten) is used in the mixture.

As used in this specification, the term ceramic material refers to asolid material produced from essentially inorganic, non-metallicsubstances which is preferably formed simultaneously or subsequentlymatured by the action of heat. See, e.g.. A.S.T.M. C-242-87,"Definitions of Terms Relating to Ceramic Whitewares and RelatedProducts."

By way of illustration, the ceramic material used may be concrete. As isknown to those skilled in the art, the term concrete refers to acomposite material that consists essentially of a binding medium withinwhich are embedded particles or fragments of aggregate.

By way of further illustration, the ceramic material used may be aceramic whiteware, that is a ceramic body which fires to a white orivory color. Methods of preparing ceramic whiteware bodies are wellknown to those skilled in the art and are described, e.g., in U.S. Pat.No. 4,812,428 of Kohut, the description of which is hereby incorporatedby reference into this specification.

In another preferred embodiment, the ceramic material is basic brick. Asis known to those skilled in the art, basic brick is a refractory brickwhich is comprised essentially of basic materials such as lime,magnesia, chrome ore, or dead burned magnesite, which reacts chemicallywith acid refractories, acid slags, or acid fluxes at high temperatures.

In yet another embodiment, the ceramic material is a refractory. As isknown to those skilled in the art, a refractory material is aninorganic, nonmetallic material which will withstand high-temperatures;such materials frequently are resistant to abrasion, corrosion,pressure, and rapid changes in temperature. By way of illustration,suitable refractories include alumina, sillimanite, silicon carbide,zirconium silicate, and the like.

By way of further illustration, the ceramic material may be a structuralceramic such as, e.g., silicon nitride, sialon, boron nitride, titaniumbromide, etc.

In another embodiment the ceramic material consists essentially of clayor shale. In this embodiment, one preferred shale which may be used isAlfred shale which is commonly available in Alfred, N.Y.

In yet another embodiment, the ceramic material consists or comprisesglass. As used in this specification, the term glass refers to aninorganic product of fusion which has cooled to a rigid configurationwithout crystallizing. See, for example, George W. McLellan et al.'s"Glass Engineering Handbook," Third Edition (McGraw-Hill Book Company,New York, 1984). By way of illustration, some suitable glasses includesodium silicate glass, borosilicate glass, aluminosilicate glass, andthe like. Many other suitable glasses will be apparent to those skilledin the art.

The above listing of ceramic materials is merely illustrative, and thoseskilled in the art will be aware of other suitable ceramic materialssuch as, e.g., those described in the January, 1991 edition of "CeramicIndustry," Volume 136, No. 1 (Business News Publishing Company, 755 WestBig Beaver Road, Suite 1000, Troy, Mich.).

In one preferred embodiment, the composition of this invention iscomprised of at least about 70 weight percent of said ceramic material(by weight of ceramic material and gluten, dry basis). In an even morepreferred embodiment, the composition of this invention is comprised ofat least about 85 weight percent of said ceramic material.

It is preferred that the composition of this invention be comprised ofat least about 0.1 weight percent of gluten and, more preferably, atleast about 0.5 weight percent of gluten. In one embodiment, one may useat least about 5.0 weight percent of gluten and, more preferably, atleast about 10 weight percent of gluten. In another preferredembodiment, the composition is comprised of at least about 20 weightpercent of gluten.

In one embodiment, discussed in greater detail elsewhere in thisspecification, the gluten may be replaced, in part or in whole, byanother binder material such gelatin, soluble fiber, and mixturesthereof. In this embodiment, the total concentration of the bindermaterial(s) is the same as that specified above for the embodiment whereonly gluten is used.

It is preferred that at least about 90 weight percent of the particlesof ceramic material are less than about 20 microns in size. At leastabout 50 weight percent of the particles of ceramic material arepreferably within the range of from about 0.5 to about 2 microns.

The mixture of the gluten and the ceramic material produced via theprocess of this invention also will have a relatively fine particle sizedistribution. It is preferred that at least about 90 weight percent ofthe particles of the mixture be less than about 20 microns in size.

The aforementioned particle size distributions refer to the condition ofthe ceramic material, and/or the mixture, when said ceramic materialand/or mixture is substantially dry, i.e., when it contians less thanabout 1.0 weight percent of liquid. Particle size distribution analysiscan be conducted by means well known to those skilled in the art; see,e.g., U.S. Pat. No. 4,282,006 of James E. Funk, the disclosure of whichis hereby incorporated by reference into this specification.

In one embodiment, the pH of the ceramic composition used in the processof this invention is from about 2 to about 8 and, preferably, from about6.5 to about 7.5. Such pH may be measured when the ceramic compositionis present in a fifty weight percent aqueous slurry.

The composition of this invention, in addition to containing both glutenand ceramic material, may contain minor amounts (from about 1 to about10 weight percent) of one or more other materials such as, e.g., pectin,gelatin, cellulose, potatoes and/or other starchy materials, glucose,maltose, eggs, vegetable oil, milk, yeast, sodium bicarbonate or otherrising agents), pepsin, and the like. Additionally, or alternatively,one may use enzymes commonly used in baking of breads such as soy flourenzyme, vitamin C, and/or other additives and preservatives commonlyused in the baking of bread.

In one embodiment, in which the binder is either a non-gluten material(such as the agar, soluble fiber, or gelatin mentioned above), or amixture of gluten and non-gluten material, the composition of thisinvention, in addition to containing such binder material, may alsocontain minor amounts (from about 1 to about 10 weight percent) of oneor more other materials such as, e.g., pectin, gelatin, cellulose,potatoes and/or other starchy materials, glucose, maltose, eggs,vegetable oil, milk, yeast, sodium bicarbonate or other rising agents),pepsin, and the like. Additionally, or alternatively, one may useenzymes commonly used in baking of breads such as soy flour enzyme,vitamin C, and/or other additives and preservatives.

In one preferred embodiment, the ceramic mixture is comprised of fromabout 1 to about 30 by weight percent (by weight of gluten in themixture) of a preservative. Suitable preservatives include potassiumsorbate, sodium propionate, undecylenic acid, zinc undecylenate,diethylpyrocarbonate, benzoic acid, sodium benzoate, BHA, BHT, sorbicacid, propionic acid, propionates, esters of parahydroxybenzoic acid,and the like. See, e.g., pages 412-413 of John M. DeMan's "Principles ofFood Chemistry" (Van Nostrand Reinhold Company, New York, 1980). It ispreferred that the preservative be selected from the group consisting ofundecylenic acid, sorbic acid, the salt of undecylenic acid, the salt ofsorbic acid, and mixtures thereof.

The aforementioned concentrations of gluten, ceramic material, andoptional other material(s) are by dry weight bases, total batch. As willbe apparent to those skilled in the art, one may determine theconcentration of a batch on a dry weight basis by drying the batch untilit contains less than about 0.1 weight percent of moisture, and thendetermining the dry weight percents of each component.

In one embodiment, in addition to containing at least 10 percent (by dryweight) of ceramic material, and the gluten, the composition of thisinvention also contains from about 20 to about 80 weight percent ofwater (by total weight of solid material and water). It is preferredthat the composition be comprised of from about 30 to about 70 weightpercent of water, by total weight of water and solids in thecomposition.

In another embodiment, the composition of this invention is comprised offrom about 1 to about 30 weight percent of an alcohol of the formula ROHwherein R is alkyl of from about 1 to about 8 carbon atoms. In oneaspect of this embodiment, the composition contains both water andalcohol.

FIG. 1 illustrates several preferred processes of applicant's invention.Referring to FIG. 1, it will be seen that, in the processes illustrated,the composition is first prepared by a mixing operation 10 prior to thetime it is utilized in other process steps.

The gluten or gluten-containing material(s), the ceramic material(s),and any other desired components in applicants' mixture may be mixed byany conventional means. Thus, for example, one may use any of the mixingdevices described in J. T. Jones et al.'s "Ceramics: IndustrialProcessing and Testing" (The Iowa State University Press, Ames, Iowa,1972). By way of illustration, one may use shell mixers, such as a twinshell or V-mixer, a double cone mixer, and the like. One may use aribbon mixer. One may use a dry color agitator. One may use a pug mill.Other well-known mixing means will be readily apparent to those skilledin the art.

It is preferred, in one embodiment, to dry mix the ingredients useduntil a substantially homogeneous mixture is obtained. Thus, e.g., suchdry mixing may be done by a ball mill. In another embodiment, theingredients are wet mixed.

After a substantially homogeneous dry mixture of gluten and ceramicmaterial is obtained, water (and/or another liquid) can be added to themixture to the desired concentration (from 20 to 80 percent, by weight)while mixing is continued. Although other liquids (such as alcohol,polyvinyl alcohol, ethers, ketones, aldehydes, organic solvents, and thelike) can be used, it is preferred to use either an aqueous system orwater. The water may be added in a pure form, or it may be added whileadmixed with another material (such as, e.g., in the form of milk).

In many of the applications for applicants' composition, the amount ofthe water in the composition will vary within the 20-80 percent range.Thus, for example, when one desires to use the composition to coat,spray dip, or brush it onto an object, it is preferred that thecomposition contain from about 45 to about 75 weight percent of water.

In one embodiment, in which corn meal is used as the gluten-containingmaterial, it is preferred to sift the corn meal to remove from it allparticles greater than about 100 microns.

Referring to FIG. 1, it will be seen that a mixture from mixingoperation 10 may be passed via line 12 to a coating or spraying ordipping or brushing operation 14. In operation 14, a film of the liquidcomposition is used to coat object to be replicated.

The thickness of the film coated onto the object to be replicated willvary depending upon the intricacy of the detail of the object. Where,for example, one wishes to replicate the shape of a flower, it ispreferred to coat a film thickness onto the flower's surfaces which isless than about 0.125 inches (after drying). On the other hand, oneoften will desire a relatively thick coat, on the order of up to about6.0 inches.

One may make a mold of an object by coating a relatively thick layer ofmaterial onto it and then burning out the object coated. Thus, withregard to the flower, if a relatively thin coat of material is coatedonto the flower, and the flower is then burned off, a relativelydelicate and fragile replication of the flower will be produced. If, onthe other hand, one wishes to produce a mold of the flower (into whichone may pour molten metal, e.g.), one should repeatedly coat the floweruntil the total thickness of the coats is at least several inches sothat, when the coated object is fired, a fired body with relatively goodphysical properties will be produced.

In one embodiment, not shown, after the object to be replicated isinitially coated with a relatively thin coat of material (from about 0.1to about 1.0 inches thick, dry), and such initial thin coat isheat-treated (as described below), a second coat of material is thenapplied to the object (such as, e.g., by dipping), and the object isheat-treated again. It will be apparent to those skilled in the art thatmany combinations and sequences of coating/spraying/dipping/brushingtogether with heat-treating may be utilized.

In general, each time a coat is applied to the object to be replicatedby one of the preferred means, such coat should be from about 0.05 toabout 0.5 inches.

It is preferred to dehydrate the object which has been coated withapplicants' composition so that it contains less than about 0.5 weightpercent of moisture. This dehydration may occur in standard dehydratingmeans (not shown), such as a dessicator. Alternatively, this dehydrationmay occur in oven 18.

After one or more coats of material have been applied to the object tobe replicated, and the coated object has preferably been dehydrated, itis preferred to heat-treat such object in either oven 18 and/orsintering furnace 24.

The coated object may be passed via line 16 to oven 18, wherein it mayheated until it has the desired porosity. The porosity may vary fromabout 5 to about 70 volume percent; it is caused by the evolution of gasfrom the mixture leaving the mixture during heating. One of the uniquefactors of applicants' process is that, notwithstanding said gasevolution, the body being heated maintains its structural integrity.Many other ceramic bodies which do not contain gluten will tend to crackupon the evolution of gas (such as water vapor).

In general, when the coated ceramic body is heated in oven 18, it ispreferred to heat such object at a temperature of from about 80 to about450 degrees Fahrenheit for from about 1 minute to about 48 hours untilthe object contains less than about 0.5 weight percent of moisture. Itwill be appreciated by those skilled in the art that the higher thetemperature used, the shorter the time which will be required.

In one embodiment, illustrated in FIG. 1, the object may be passeddirectly to the sintering furnace 24 without heating it in the oven; inthis embodiment, the dehydration of the coated object occurs in thesintering furnace, preferably as the furnace is raised from ambient tothe sintering temperature. Thus, referring again to FIG. 1, the coatedobject may be passed to oven 18 via line 16 and, thereafter, tosintering furnace 24 via line 22; alternatively, it may be passeddirectly to sintering furnace 24 via line 20.

The sintering step is generally used when an object with relatively goodmechanical properties is required. In general, the coated, dehydratedobject is sintered by subjecting it to a temperature of from about 1,500to about 3,200 degrees Fahrenheit for from about 0.5 to about 24 hours.

In another embodiment of applicants' invention, applicants' compositionis charged to a container in which it is allowed to expand and, thus, toconform to the interior shape of the container. In this embodiment, itis preferred to use a composition which contains from about 20 to about80 percent of water. One may use a dough-like composition (whichcontains from about 20 to about 30 weight percent of water), one may usea slurry (which contains from about 45 to about 75 weight percent ofwater), and may use any composition in between.

The composition is charged from mixing operation 10 via line 26 tocontainer 28. It is preferred that container 28 consist of a cavitywhich describes the shape of an article to be reproduced; and thematerial will be charged within said cavity and thereafter heat-treated.When it is so heat-treated, it will expand and adopt the shape of saidcavity. Upon sintering, a shaped object will be produced which issubstantially identical to the shape of the cavity.

In one embodiment, the container burns off during sintering, leavingonly a shaped body which replicates the shape of the cavity. In anotherembodiment, the container does not burn off during sintering, leaving acontainer which must be mechanically removed from the shaped objectwithin it.

After the composition has been charged to container 28, it is preferredto dehydrate the composition so that it contains less than about 0.5weight percent of moisture. One may dehydrate it by passing it to oven36 via line 32 in the manner described above. Alternatively, one maypass it directly to the sintering furnace 24 where it can be sintered inthe manner described above.

Alternatively, one may pass the mixture via line 30 to microwave oven34. The use of microwave oven 34 dehydrates the coated object relativelyrapidly. One may use any conventional microwave, and preferably thecoated object will be subjected to microwave radiation at frequency offrom about 0.9 to about 22.1 Gigahertz. See, e.g., U.S. Pat. No.4,872,896, the disclosure of which is hereby incorporated by referenceinto this specification.

In one preferred embodiment, where microwave oven 34 is used, it ispreferred to irradiate the coated object using the "high" setting. Inthis embodiment, one should preferably subject the coated object to themicrowave radiation for at least about 5 minutes per pound of coatedobject.

One advantage of the microwave oven 34 is that it produces asubstantially larger pore size distribution. Once the coated object hasbeen dehydrated and, when appropriate, heated in the sintering furnace,a porous ceramic structure is produced which has a porosity of fromabout 1 to 80 volume percent. As will be apparent to those skilled inthe art, the porosity of the finished product and the amount of glutenwhich originally was in the coated material are related.

As is known to those skilled in the art, the porosity of a ceramicobject may be determined in accordance with A.S.T.M. Standard TestC373-72 (Reapproved 1982), "Standard Test Method for Water Absorption,Bulk Density, Apparent Porosity, and Apparent Specific Gravity of FiredWhiteware Products."

In one preferred embodiment, the apparent porosity of the center of thefinished product is from about 1 to about 15 volume percent. In anotherembodiment, the apparent porosity of the center of the finished productis from about 16 to about 30 volume percent. In yet another embodiment,the apparent porosity of the center of the finished product is fromabout 31 to about 45 volume percent. In yet another embodiment, theapparent porosity of the center of the finished product is from 46 toabout 80 volume percent.

The center of the finished product of applicants' invention exhibitsopen cell porosity. Thus, in applicants' structure, there is apredominance of interconnected cells. The test for apparent porosity,mentioned above, determines the effective open cell porosity.

One unique feature of applicants' process is that, even with firedbodies which have in excess of 95 percent of their theoretical density,open (effective) porosity still exists. Heretofore, it did not appear tobe possible to obtain such a combination of high density and effectiveporosity. Thus, for example, in the classic work by W. D. Kingery et al.entitled "Introduction to Ceramics," Second Edition (John Wiley andSons, Inc., New York, 1976), it is disclosed (at page 521) that "Beforefiring, almost the entire porosity is present as open pores. Duringfiring, the volume fraction porosity decreases . . . . Although someopen pores are eliminated directly, many are transformed into closedpores. As a result, the volume fraction of closed pores increasesinitially and only decreases toward the end of the firing process. Openpores are generally eliminated when the porosity has decreased to 5% . .. . By the time 95% of theoretical density is reached, the ware isgastight."

The open porosity of a fired ceramic body may be determined by mercuryinstrusion porosimetry. As is known to those skilled in the art, mercuryintrusion porosimetry may be used to define the average pore size, thepore size distribution, the bulk density, and the skeletal density ofnon-compressible solids. The pore structure analysis by mercuryintrusion is based on measuring the volume of mercury forced into thepores of the sample as a function of presssure. The pressure at whichintrusion into the pores occurs is inversely proportional to porediameter. See, e.g., pages 261-264 of John P. Sibili's "A Guide toMaterials Characterization and Chemical Analysis" (VCH Publishers, Inc.,New York, 1988).

In the mercury intrusion porosimetry test, the sample must be solid andnon-compressible if pore measures of less than ten microns are desired.Sample quantities required are nominally 0.3 to 1.0 grams.

The fired samples produced by the process of this invention, when testedin accordance with the mercury intrusion porosimetry test, willpreferably have a total apparent porosity of at least about 7 volumepercent and, more preferably, at least about 30 volume percent. As willbe apparent to those skilled in the art, apparent porosity is therelationship of the open pore space to the bulk volume, expressed inpercent.

The fired samples also have a median pore diameter of from 0.3 micronsto about 50 microns, as determined by the mercury intrusion porosimetrytest. It is preferred that the median pore diameter of the fired samplesbe from about 0.3 to about 2.0 microns.

The distribution of pores in applicants' finished product issubstantially different than the pore distribution obtained in prior artproducts; and the distribution of pores in applicants' device allows fora more effective flow of liquid and/or gas through the porous structure,providing a combination of optimal surface area and ease of flowproperties to the structure. As is known to those skilled in the art,the higher the specific surface area of a filter, the greater thefiltration effect. However, when all of the pore sizes in a filter arerelatively small, the flow rate of material through the filter may berelatively slow. Applicant's product provides an improved combination ofeffective filtration and reasonable flow rate properties.

In one preferred embodiment, the center section of one porous productproduced in applicants' process by baking contains from about 5 to about40 volume percent of pores with a mean pore diameter of less than about1 micron. As is known to those skilled in the art, one may determine themean pore diameter of the pores of a body by examining the body on ascanning electron microscope. Thus, for example, one may use a DSM 940Digital Scanning Electron Microscope, which is manufactured by andavailable from Carl Zeiss Inc., One Zeiss Drive, Thornwood, N.Y.

To determine the mean pore diameter, the object so baked is cut throughits centerline using, e.g., a variable speed rotary tool. One may useany suitable variable speed rotary tool such as, e.g., Sears andRoebuck's variable speed rotary tool, model number 9A61003, equippedwith a 3/8" cone silicon carbide abrasive point (available from Searsand Roebuck Company, Chicago, Ill. 60684).

Once the baked and sintered object has been cut through its centerline,the newly exposed surface is then examined under a camera microscopeequipped with a reticle. Thus, e.g., one may use optical microscope,model number SD 3900-00, (available from the Cole-Parmer InstrumentCompany of 7425 North Oak Park Avenue, Chicago, Ill. 60648) equippedwith a Polaroid SX-70 camera (model number SD-3910-00), both of whichalso are available from the Cole-Parmer Instrument Company. The opticalmicroscope is provided with a reticle, such as reticle 04RET011,available from Melles Griot Company of 1770 Kettering Street, Irvine,Calif. 92714.

Using this equipment, a picture of the ground surface of the sinteredceramic sample is taken, and the number of pores per unit area within aspecified pore size range is determined. However, when determining thenumber of pores which are from about 1.0 micron to 100 microns, it ispreferred to use the scanning electron microscope.

In the preferred embodiment described above, it is also preferred thatfrom about 7 to about 60 volume percent of the pores in the center ofthe finished body, when tested by the aforementioned test, have a meanpore diameter of from about 1 to about 10 microns. As will be apparentto those skilled in the art, reference to the term "about 7 to about 60volume percent" implies that those pores which have a mean pore diameterof from about 1 to about 10 microns in the center section account forfrom about 7 to about 60 volume percent of the porosity of the groundsection.

In the embodiment described above, and with respect to said section, itis preferred that from about 10 to about 60 volume percent of the poresin the center of the finished body have a mean pore diameter of fromabout 11 to about 100 microns, that from about 5 to about 65 volumepercent of the pores in the center of the finished body have a mean porediameter of from about 101 to about 500 microns, that from about 3 toabout 70 volume percent of the pores in the center of the finished bodyhave a mean pore diameter of from about 501 to about 1,000 microns, andthat from about 0 to about 75 volume percent of the pores in the centerof the finished body have a mean pore diameter in excess of 1millimeter.

In one preferred embodiment, wherein the coated body is either baked ormicrowaved, a "crust" is preferably formed on the outside surface of theobject. This crust, which generally is from about 1 millimeter to about2 centimeters in thickness, has a porosity of from about 1 to about 40volume percent. In general, the porosity of the crust section is fromabout 3 to about 40 percent of the porosity of the center section.

As will be readily apparent to those skilled in the art, the poredistribution of the crust can be determined by examining such crust withthe equipment and procedures described above. Thereafter, the poredistribution of the center of the sintered body may be similarlyexamined, and the relationship of the two pore distributions may bedetermined.

The crust has a pore size distribution, as measured above, such that atleast about 15 volume percent of the pores in the finished product havea mean pore diameter of less than 1 micron. As will be apparent to thoseskilled in the art, this means that those pores in the crust which havea mean pore diameter of less than about 1 micron represent at least 15volume percent of the total porosity of the crust.

In the embodiment described above, from about 10 to about 60 volumepercent of the pores in the crust have a mean pore diameter of fromabout 1 to about 10 microns, that from about 10 to about 60 volumepercent of the pores in the crust have a mean pore diameter of fromabout 11 to about 100 microns, that from about 1 to about 10 volumepercent of the pores in the crust have a mean pore diameter of fromabout 101 to about 500 microns, that from about 1 to about 7 volumepercent of the pores in the crust have a mean pore diameter of fromabout 501 to about 1,000 microns, and 0 volume percent of the pores inthe crust have a mean pore diameter in excess of 1 millimeter.

FIG. 24 is a sectional view which illustrates, for one product 37 whichhas been baked and sintered in applicants' process, the porosity of thecrust section 38 and the center section. It will be seen that the crustsection 38 contains smaller pores than center section 40 and,consequently, has a lower porosity.

Referring again to FIG. 1, the composition from mixing operation 10 maybe passed via line 42 to molding operation 44. In one preferredembodiment, the composition is molded in operation 44 by hot-pressing.As is known to those skilled in the art, hot pressing is baking duringthe application of external pressure. In this aspect of the moldingprocess, a pressure of from about 18 to about 175 pounds per square inchand a temperature of from about 200 to about 600 degrees Fahrenheit isused in the hot pressing for from about 1 second to about 10 minutes.

It is preferred to hot press the composition at a pressure of about 18to about 50 pounds per square inch and a temperature of from about 350to about 450 degrees Fahrenheit for from about 2 to about 5 minutes.

Referring again to FIG. 1, the object which has been molded (such as,e.g., by hot pressing) may be passed directly via line 46 to sinteringfurnace 24. Alternatively, the object may be passed via line 48 to oven50, to further dehydrate it until it contains less than about 0.5 weightpercent of moisture. One may heat the object in oven 50 to a temperatureof from about 100 to about 450 degrees Fahrenheit for a time sufficientto dehydrate it to the desired level. Thereafter, the dehydrated objectmay then be passed to the sintering furnace 24 via line 52.

Referring again to FIG. 1, it will be seen that the composition which issubjected to the self-rising operation described elsewhere may be passeddirectly to sintering furnace 24 via line 56. Alternatively, and asdescribed elsewhere in this specification, the composition may first becharged into microwave oven 34 and thence via line 54 to sinteringfurnace 24. Alternatively, or additionally, the composition may becharged to oven 36 and thence via line 58 to sintering furnace 24.

FIG. 2 illustrates one preferred means of replicating fine objects suchas, e.g., a flower 60. Although a flower is used to illustrate thisreplication process, it will be apparent that any other fine object canbe replicated such as, e.g., a poodle.

When replicating fine objects, such as flower 60, it is preferred thatthe composition used be a water-based slurry which contains from about40 to about 95 weight percent of water (by combined weight of water andsolids). The solid material in the slurry will preferably contain fromabout 10 to about 40 weight percent of gluten and from about 90 to about60 weight percent of ceramic material, both by combined weight of glutenand ceramic material.

In one aspect of this embodiment, it is preferred that the slurry usedcontain the ceramic materials present in casting slips which can producea porcelain body. These casting slips are well known to those skilled inthe art and are described, e.g., in James Chappell's "The PottersComplete Handbook of Clay and Glazes" (Watson-Guptill Publications, NewYork, N.Y., 1977). Thus, the ceramic portion of the formulation maycontain (1)46 parts of kaolin, 34 parts of flint, 19.8 parts offeldspar, and 1.2 parts of sodium carbonate, (2)22 parts of Kentuckyball clay #4, 20 parts of Tennessee ball clay #1, 58 parts of nephelinesyenite, 1.6 parts of sodium carbonate, (3) 51 parts of kaolin, 29.7parts of feldspar, 19 parts of flint, 0.3 parts of sodium carbonate.

As is well known to those skilled in the art, and as is described inU.S. Pat. No. 4,812,427, the porcelain casting slip often will containfrom about 25 to about 39 parts of ball clay, from about 11 to about 25parts of kaolin, from about 40 to about 55 parts of nonplastics(potassium and sodium aluminosilicates and flint, such as feldspar,nepheline syenite, feldspathic sand, flint, calcined clays, talc,pyrophylite, and the like).

Referring again to FIG. 2, the slurry in sprayer 62 is sprayed ontoflower 60 until a coating with a thickness of about 0.06 to about 0.25inches is produced, thereby producing coated flower 64. In oneembodiment, the coated flower 64 is then charged to oven 36, where it ispreferably heated under atmospheric conditions to a temperature of fromabout 100 to about 450 degrees Fahrenheit until it contains less thanabout 0.5 weight percent of moisture; the amount of moisture in thecoated flower 64 may be determined by conventional means. In anotherembodiment, not shown, the coated flower 64 may be charged directly tosintering furnace 24, in which, as the temperature is slowly raised, itbecomes dehydrated and sintered. In this latter embodiment, it ispreferred to raise the temperature of the furnace at a rate of fromabout 1 to about 5 degrees Fahrenheit per minute.

Once flower 64 has been suitably dehydrated in oven 36, it may be eithercoated and dehydrated again, and/or charged to a sintering furnace 24(not shown).

When the coated flower 64 is in the sintering furnace 24, it usuallywill be subjected to a temperature of from about 1,100 to about 2,600degrees Fahrenheit and, thus, will have its organic portion burned out.Thus, the flower 60 and the gluten in the composition will burn out,leaving a porous, sintered replica 66 of the flower 60 with a hollow,replicated core 68.

FIG. 3 illustrates a baking process in which the composition of thisinvention expands during baking to fill a cavity within a mold.Referring to FIG. 3, it will be seen that container 70 is comprised ofapplicants' composition which, preferably, contains from about 20 to 60weight percent of water (by total weight of composition). Thiscomposition is charged into mold 72 until it fills a portion of suchmold. Because the water/ceramic/gluten mixture expands during baking, itis preferred to fill mold 72 only up to about line 74 so that the mold72 is only partially filled. In general, from about 20 to about 60volume percent of the mold is filled with the composition, although itis preferred to fill mold 72 so that about 45 to about 55 volume percentof it is filled.

In one embodiment, yeast and/or one or more enzyme(s) are added to thecomposition, causing it to rise without heating and produce the risenloaf 76. In another embodiment, the partially filled mold 72 is passedvia line 78 and/or 80 for further thermal processing.

Referring again to FIG. 3, either the partially filled mold 72 and/orthe risen loaf 76 can be treated in microwave oven 34 and thereaftertreated in sintering furnace 24 to produce porous sintered body 86. Inthis embodiment, the material is first baked in the sintering oven (at atemperature of from about 100 to about 450 degrees Fahrenheit) andthereafter sintered. It should be noted that, inasmuch as the mold 72consisted of organic material in the embodiment illustrated in FIG. 3,it burned out during sintering, leaving only the porous ceramic body 86.

Referring again to FIG. 3, either the half-filled mold 72 and/or therisen loaf 76 may be charged directly to sintering furnace 24, in whichit may also be initially baked and thereafter sintered. In somesituations, which are illustrated in FIG. 3, the direct baking andsubsequent sintering of the risen loaf sometimes will cause a cavity 88to form in sintered body 90. This phenomenon generally does not occurwhen the composition is first subjected to microwave treatment.

FIG. 4 illustrates a relatively low-temperature low-pressure moldingprocess. In this embodiment, the composition of this invention ischarged to a container 92. This composition may contain from about 20 toabout 60 weight percent of water. The composition from container 92 maybe charged onto the forming surfaces of hot waffle iron 94, usually to athickness of from about 0.25 to about 1.0 inch. Thereafter, the waffleiron 94 is closed, subjecting the aqueous composition to a slightpressure. The composition is maintained within waffle iron 94 for fromabout 1 to about 10 minutes, thereby forming waffle 96. The temperaturewithin waffle iron 94 is generally from about 200 to about 450 degreesFahrenheit.

The waffle 96 is then charged to sintering furnace 24 where it issubjected to a temperature of from about 1,100 to about 2,600 degreesFahrenheit to form a sintered body 98.

FIGS. 5, 6, 7, and 8 illustrate one preferred use of applicants' processto make a ceramic burner element which, when used with a liquid fuel,acts as a ceramic wick. Referring to these Figures, it will be seen thatceramic wick 100 is preferably comprised of contiguous layers 102 and104, each with different porosities. The wick 100 is disposed within apool of flammable liquid 106 (such as kerosene), or natural gas 106(such as propane), and the upward flow of said liquid or gas ispartially prevented by the presence of barrier 108. Because the porosityof layer 102 is lower than that of layer 104, the liquid fuel 106 iswicked up layer 102 and may be ignited to form flame 110.

As will be apparent to those skilled in the art, the ceramic wick 100may be comprised of many layers with many different arrangements ofporosity, thickness, and configuration. Thus, by way of illustration,and referring to FIG. 6, the wick of this embodiment has an inner layer112 with a larger porosity than that of intermediate layer 114 or outerlayer 116. Thus, by way of further illustration, the wick of FIG. 7 iscomprised of an outer layer 118, an inner layer 120, and a reflector 122which tends to direct the heat produced by the wick. Thus, by way offurther illustration, the ceramic wick of FIG. 8 is comprised of aninner layer 124 with a relatively large porosity, a first intermediatelayer 126 with a smaller porosity, a second intermediate layer 128 witha porosity larger than that of the inner layer 124, and an outer layer130 with a porosity larger than that of the inner layer 124. As will beapparent to those skilled in the art, by sequentially coating and firingan object with different gluten/ceramic compositions, one may formcontiguous layers of material with different porosities.

FIG. 9 illustrates a burner assembly 132 which is comprised of a gasinlet 134, valve 136, cap 138, and ceramic diffuser body 140. Dependingupon the pressure of the gas fed into the diffuser, a flame 142 can becaused to appear at various points of the ceramic body 140.

FIG. 10 illustrate the sintered body 66 connected to a source of neonplasma (not shown) by pipe 144. Disposed within pipe 144 is an electrode(not shown) which will excite the plasma 146.

FIG. 11 illustrates the use of a porous body 148 to feed nutrients tothe roots 150 a plant 152 and to act as an anchoring medium. Both waterand nutrients may be fed in the direction of arrow 154 into body 148, towhich roots 150 are attached and with which they communicate.

FIG. 12 is a sectional view illustrating a particulate filter 156.Filter 156 is comprised of frame 158 and filter body 160.

FIG. 13 is a sectional view illustrating a planting pellet 162 which iscomprised of wedge 164, porous ceramic container 166, and seed 168. Theentire pellet is inserted into the ground. As the seed germinates, itsroots spread through ceramic container 166.

In one embodiment, the porous ceramic container 166 is comprised of orconsists essentially of a ceramic material which is partially watersoluble and will release nutrients gradually. These water-solubleglasses are well known to those skilled in the art.

FIG. 14 illustrates a hydroponic container 170 which is comprised ofwall 172, porous medium 174, and liquid 176. Plants may extend rootsthrough the pores of medium 174 towards liquid 176. As will be apparentto those skilled in the art, the liquid 176 may be a suitable nutrientsolution.

FIG. 15 illustrate yet another hydroponic system 178 which is comprisedof a reservoir 180 of nutrient solution which is connected to a pump182. Pump 182 forces nutrient solution through pipe 184 into the top ofpipe 186. Within pipe 186 is disposed a porous ceramic body (not shown).Holes 188 in pipe 186 allow the roots of plants (not shown) tocommunicate with the porous ceramic body within pipe 186.

FIG. 16 is a sectional view of a hydroponic apparatus 190 comprised of anutrient fluid input 192, a holder 194, a porous ceramic body 196disposed within and retained by holder 194, and aeration vents holes198. In the operation of this device 190, nutrient fluid is forced upthrough said delivery pipe 192 and aeration vent holes 198 andcommunicate with a plant (not shown) contiguous with the surface ofceramic body 196.

FIG. 17 illustrates a means of forming a composite material. Inaccordance with the process described elsewhere in this specification, aporous, sintered ceramic body 200 is formed. Thereafter, by conventionalinfiltration techniques, either molten polymeric material (such as,e.g., synthetic polymers such as nylon, polyester, Kevlar, polyvinylchloride, and the like) and/or molten metal is infiltrated partially orcompletely into the surface(s) of the porous body 200.

FIG. 18 is a perspective view of a roof tile 202 made by the process ofthis invention. In the embodiment illustrated, the exterior surfaces 204of roof tile 202 are glazed.

Preparation of a Cermet by Electrochemical Means

In one preferred embodiment of this invention, a cermet material isprovided by an electrochemical process in which one of the electrodes isdisposed within a porous body which, preferably, is made by the processof this invention. This process is illustrated in FIG. 19.

Referring to FIG. 19, a metal cathode 206 is disposed within a porousceramic body 208 which has open cell porosity. Porous ceramic body 208may be made by the process of this invention, or it may be made by otherprocesses, as long as it has open cell porosity.

In one embodiment, ceramic body 208 is made by the process of thisinvention by coating applicants' ceramic composition onto a metalsubstrate and then firing the coated metal substrate. In anotherpreferred embodiment, the ceramic porous body 208 is first prepared, andcavity is provided within it, and the metal cathode is disposed withinit.

Referring again to FIG. 19, metal anode 210 is connected to the negativeterminal 212 of power source 214. Electrons flow from power source 214,to anode 210 (where metal ions are formed), through solution 216, tocathode 206. As will be apparent to those skilled in the art, solution216 preferably is comprised of a solution of a metal compound whereinthe metal cation is the metal of anode 210. The metal ions in solution216 pass through the pores of porous body 208 and accrete upon thesurface of metal cathode 206. As this process continues, the pores ofthe ceramic body 208 become filled with metal.

In one preferred aspect of this embodiment, after the electroplatingoperations has been completed, the metal cathode/ceramic body assemblyis then placed in an oven (not shown) and heated to more firmly andhomogeneously distribute the metal throughout the pores of ceramic body206.

As will be apparent to those skilled in the art, when the metal of anode210 differs from the metal of cathode 206, a potential differencearises. Thus, if one removes the power source from the device of FIG.19, a battery results. This battery structure is illustrated in FIG. 20.

FIG. 21 illustrates a bone patch material which can be made by theprocess of this invention. Referring to FIG. 21, bone patch ispreferably comprised of a multiplicity of layers such as laminatedlayers 220, 222, 224, 226. These laminar layers may be made by thesequential deposition process described elsewhere in this specification.They resemble the laminar structure of many bones and, thus, should becompatible therewith. In one aspect of this embodiment, the ceramicmaterial used is calcium phosphate.

Because of the flexibility of applicant's process, one can produce abone-like structure with a porosity distribution which closely simulatesthat of naturally-occurring bone.

FIG. 22 illustrates a toxic waste disposal container 228 which iscomprised of an impervious outer shell 230, a porous intermediate layer232. If, by some accident, container 228 were to rupture, porousmaterial 232 would tend to absorb and retain the toxic waste.

FIG. 23 illustrates a burner core 234 into which pressurized gas is fedin the direction of arrow 236. By varying the porosities of layers 238,240, and 242, one can affect the occurrence and intensity of the flamewithin this core.

FIG. 25 illustrates a forming process in which a ceramic green body isfirst formed around one or more noodles 240 which are comprised ofgluten-containing material. These noodles may be formed by conventionalnoodle-forming techniques to any desired shape(s). Thereafter, either aceramic material (such as clay) or a ceramic/gluten mixture (such asapplicant's composition) is formed around them. The green body is thenprocessed so that, ultimately, the noodles and/or the gluten burn out. Asintered ceramic body 250 comprised of channels where the noodles 248had appeared and pores (in case a ceramic/gluten mixture is used) areformed.

FIG. 26 illustrates a process in which a metal casting body may beformed. Referring to FIG. 26, it will be seen that, in the first step ofthis process, the object to be replicated 252 (a tree branch) is coatedwith the composition of the invention to form a coated body 254 which,thereafter, is fired to form a hollow sintered body 256. Molten metal258 is poured within the cavity of body 256 and allowed to cool.Thereafter, the ceramic shell of body 256 is broken off the cooled metalby conventional means such as, e.g., hammer 260, and the metal replica262 of the object to be replicated 252 is removed.

Preparation of a Filter Body With Substantial Porosity

FIG. 27 is a flow diagram illustrating a preferred process ofapplicants' invention in which a body with substantial porosity and poredistribution uniformity is produced.

The distribution of pores in applicants' finished product issubstantially different than the pore distribution obtained in prior artproducts; and the distribution of pores in applicants' device allows fora more effective flow of liquid and/or gas through the porous structure,providing a combination of optimal surface area and ease of flowproperties to the structure.

The properties of the porous body made in accordance with the procedureof FIG. 27 are similar to the properties of the porous bodies describedelsewhere in this specification. However, one substantial difference isthat less than 1.0 volume of the pores in the body produced by theprocess of FIG. 27 are larger than the maximum pore size of thesponge-like material used in such process. Thus, depending upon theproperties of the sponge-like material chosen for the process, the poresize distribution also will vary.

In one embodiment, the average pore diameter of the sponge used inapplicants' process does not exceed 3.0 centimeters. In anotherembodiment, the average pore diameter of the sponge-like material usedin applicants' process does not exceed 1.0 centimeter. In yet anotherembodiment, the average pore diameter of the sponge material is lessthan 5 millimeters. In yet another embodiment, the average pore diameterof the sponge like material does not exceed about 1 millimeter. In yetanother embodiment, the average pore diameter of the sponge-likematerial does not exceed 500 microns. In yet another embodiment, theaverage pore diameter of the sponge-like material does not exceed 100microns. In yet another embodiment, the average pore diameter of thesponge-like material does not exceed 20 microns.

Referring to FIG. 27, and in the preferred process described therein, asponge-like material (not shown) is saturated in step 280.

As is known to those skilled in the art, a sponge is an material is anorganic (carbon-containing) material which be any of numerous,primitive, chiefly marine animals of the phylum Porifera composed offibrous material. Furthermore, any of various substances havingspongelike qualities (such as certain forms of plastics, rubber, orcellulose) also may be used as sponge in applicants' invention.

Thus, by way of illustration and not limitation, the sponge materialused in the process may be the cellular skeleton of a marine animal ofthe genus Spongia.

Thus, by way of further illustration, the sponge material may be acellular plastic. As is known to those skilled in the art, a cellularplastic is a thermosetting or thermoplastic foam composed of cellularcores with integral skins having high strength and stiffness; the cellsresult from the action of a blowing agent, either at room temperature orduring heat treatment of the plastic material.

By way of further illustration, the sponge material may be a solid foam(such as sponge rubber), which is a dispersion of gas in a liquid orsolid.

By way of further illustration, one may use the organic sponge-likematerials described in U.S. Pat. Nos. 5,035,468 (open cell organicsponge), 5,107,861, 5,106,969 (marine sponge), 5,105,827 (elastic foamsponge), 5,104,350, 5,103,729, 5,100,384, 5,099,684, 5,099,541,5,096,946 (cellulosic sponge), 5,093,381 (rubber sponge), 5,091,412(marine sponge), 5,081,740 (sponge rubber), 5,073,202, 5,071,648(polyvinyl acetate sponge), 5,071,347 (synthetic sponge), 5,058,211(polyurethane sponge), 5,039,414, 5,018,300, 5,013,660 (sponge plastic),4,991,841 (sponge rubber), 4,959,341 (polyanionic carbohydrate),4,957,810 (synthetic sponge), 4,925,924 (collagen sponge), 4,925,327(foam sponge), 4,904,469 (polysaccharide sponge), and the like. Theentire disclosure of each of these United States patents is herebyincorporated by reference into this specification.

The sponge material used in the process of this invention is preferablyorganic. The term organic, as used in this case, refers to a spongematerial which, when subjected to a temperature of 800 degrees Celsiusfor 60 minutes, will "burn out," i.e., will be substantially entirelyconverted to gaseous material. As those skilled in the art are aware,the sponge material may contain some impurities which will not vaporizeat 800 degrees Celsius. However, as long as at least about 95 weightpercent of the sponge material is converted to gas when subjected to 800degrees Celsius for 60 minutes, such material may be used in applicants'process.

In one preferred embodiment, the sponge-like material used inapplicants' process is either an elastic foam sponge (sold under thename of "O-CELL-O" by the Minnesota Mining and ManufacturingCorporation), a polyurethane foam sponge. In another embodiment, thesponge material is loofa.

The ceramic mixture described elsewhere in this specification ispreferably in the form of a slurry, and such slurry preferably is usedto substantially saturate the sponge material. In this embodiment, theslurry contains from about 45 to about 75 weight percent of solidmaterial and from about 55 to about 25 weight percent of liquid, such aswater. Referring to FIG. 27, the slurry (not shown) may be charged vialine 282.

The ceramic mixture which is described elsewhere in this specification,which is preferably comprised of ceramic material and gluten, is used tosubstantially saturate the sponge material so that said sponge materialcontains from about 95 to about 100 percent of the maximum amount it canhold of such mixture. One can determine the maximum amount of slurrythat can be held by determining the weight of slurry in a container,thereafter compressing the sponge material until it has attained itsstate of substantial maximum density, thereafter immersing thecompressed sponge material in the slurry, and thereafter removing thecompressive force upon the sponge material and allowing it to expand andpick up slurry, and thereafter removing the sponge material from theslurry. The container with the slurry can then again be weighed todetermine the amount of slurry picked up. This is the saturation amount.

The sponge saturation process may be conducted under ambient conditions.Alternatively, one may use super- or subatmospheric pressure conditions.

Any conventional means may be used to substantially saturate the spongematerial. Thus, e.g., the sponge material may be immersed in the slurry,the slurry may be sprayed onto and/or through the sponge material, etc.

When the sponge material used in the process of FIG. 27 has a maximumpore size of less than about 600 microns, it is preferred to subject thesubstantially saturated sponge material to ultrasound treatment. Thus,referring to FIG. 27, the saturated sponge may be passed via line 284 toultrasound chamber 286 and exposed to ultrasonic vibration at afrequency of greater than about 20,000 hertz for at least about 5minutes.

After the sponge material has been saturated and, optionally, subjectedto ultrasonic treatment, it is dehydrated until it contains less thanabout 5.0 weight percent of liquid. It is preferred to conduct thedehydration until the sponge material contains less than about 2.0weight percent of liquid. It is even more preferred to dehydrate thesponge material until it contains less than about 1.0 weight percent ofliquid. In the most preferred embodiment, the sponge material isdehydrated until it contains less than about 0.5 weight percent ofliquid.

Any conventional means may be used to dehydrate the saturated spongematerial. Thus, for example, one may allow to air dry, heat it undervacuum or under ambient conditions, flow air (or other gas) over thesponge material, charge the sponge to a dessicator, etc.

Three preferred dehydrating means are illustrated in FIG. 27. Thus,referring to FIG. 27, the saturated sponge which has not been subjectedto ultrasonic frequency may be charged via line to line 290. Thesaturated sponge which has been subjected to ultrasound treatment may becharged via line 292 to line 290.

Referring again to FIG. 27, in one embodiment, the saturated sponge ispassed via lines 290 and 294 to microwave chamber 296. In general, foreach 50 grams of weight of saturated sponge, the sponge will besubjected to microwave radiation for at least about 40 seconds and,preferably, for at least 60 seconds. It is preferred not to expose thesaturated sponge for more than about 2 minutes for each 50 grams ofsaturated sponge.

Alternatively, one may pass the saturated sponge via lines 290 and 298to oven 300. Additionally, the microwaved sponge from microwave unit 296may also be passed via line 302 to oven 300.

It is preferred to heat the saturated sponge in oven 300 to atemperature of from about 300 to about 450 degrees Fahrenheit andsubject the sponge to such temperature for at least about 2 minutes. Inone embodiment, the saturated sponge is heated for from about 10 toabout 30 minutes at a temperature of from about 325 to about 375 degreesFahrenheit.

In another embodiment, the saturated sponge is passed via lines 290 tohot press 306. The hot pressing conditions described on page 21 of thisspecification may be used in hot press 306 to dehydrate and/or form thesponge material. Thus, e.g., one may use a waffle-iron type of apparatusto dehydrate and form the saturated sponge.

In one embodiment, during the microwave treatment and/or the ovenheating treatment and/or the hot pressing treatment, the saturatedsponge material may be enclosed within a mold so that, while it is beingdehydrated, it will tend to take the shape of the mold.

In one embodiment, illustrated in FIG. 27, the dehydrated spongematerial may be machined prior to the time it is fired in furnace 308;thus, the dehydrated sponge may be passed via line 310, or 312, or 314to machining operation 316. This machining step, which is optional, maybe used to grind one or more of the sponge's surfaces, to cut the spongeto a desired shape, to drill holes in the sponge material, and the like.Applicants' process produces a dehydrated sponge with sufficient greenstrength to allow such machining operations.

The dehydrated sponge, with or without machining, is passed via line 318to furnace 308, where it is heated to a temperature of at least about1,500 degrees Fahrenheit and, preferably, from about 1,500 to about3,200 degrees Fahrenheit in accordance with the procedure describedelsewhere in this specification. During this firing process, the spongematerial burns out, leaving a fired, strong, porous ceramic body. Thisceramic body may be treated and/or used as described elsewhere in thisspecification.

In one preferred embodiment, not shown, the gluten is mixed with a glazecomposition. In this embodiment, from about 1 to about 15 weight percentof gluten is mixed with from about 99 to about 85 weight percent ofglaze. The incorporation of the gluten into the glaze composition willflocculate the glaze and prevent it from flaking, cracking, crawling,creeping, and pinholing.

Process for Preparing a Micoreticulated Filter Body

Applicants' have developed yet another process for producing a firedbody with a fine pore size distribution. This process, which isdescribed in more detail in the Examples of the case, is characterizedby the use of the ceramic/gluten/water mixture described elsewhere inthis specification with the particular particle size distributionmentioned.

The following examples are presented to illustrate the claimed inventionbut are not to be deemed limitative thereof. Unless otherwise specified,all temperature are in degrees Celsius, and all parts are by weight.

Example 1

Replication of the Shape of a Flower

In the experiment of this Example, a daffodil which was obtained at theAlfred Greenhouse of in Alfred, N.Y. was coated with a specified mixtureand then burned out. This daffodil was approximately 4 inches in lengthafter the stem was cut.

The mixture used to coat the daffodil contained kaolin, silica,feldspar, soda ash, and gluten. This mixture was prepared by charging 46grams parts of "EPK kaolin," 34 grams of flint, 19.8 grams of feldspar,and 1.2 grams of soda ash to a 1-gallon bucket; each of theseingredients, as it was charged to the bucket, was sifted through a 100mesh sieve.

The ingredients were mixed for about 15 minutes until a substantiallyhomogeneous mixture was obtained. Thereafter, to this mixture wascharged 25 grams of vital wheat gluten which was purchased from theZieglers Company of 6890 Kinne Street, East Syracuse, N.Y. as catalognumber 058030. This mixture also was sifted and hand mixed for about 15minutes.

To this mixture was charged 100 grams of water to produce a 80 weightpercent slurry. The water/solids mixture was then charged to a blender.

The slurry in the blender was blended at a medium speed for 15 minutes.Thereafter, blended slurry was charged to a spray gun.

The surfaces of the daffodil were then sprayed with the material in thespray gun until each of the surfaces was coated with material with athickness of about 0.0625 inches. The coated daffodil was then dried byplacing it into a test kiln. The temperature of the kiln was 93 degreeCelsius, and the coated flower was maintained at this temperature for 10minutes.

The dried flower was then removed from the kiln, and another coat ofmaterial of about 0.0625 inches was sprayed onto it. Thereafter, theflower was then put back into the kiln and fired to cone 9.

The fired object, which replicated the shape of the daffodil, was thenremoved from the kiln.

Example 2

Replication of the Shape of a Carnation

The procedure in example one was used to coat a carnation. The ceramicgluten mixture was prepared in the same manner as in example 1. Thecarnation was spray coated and charged to a 93 degree Celsius kiln for15 minutes, removed and sprayed a second time, and placed in the 93degree kiln for an additional 40 minutes. The coated carnation was thenremoved from the kiln and dipped in a second mixture that was preparedwith the same materials and proportions as in example one with theexception of the water content. The water content was reduced to 50.4grams of water to produce a 40 weight percent slurry. After dipping thecoated carnation in the 40 weight percent slurry, a 0.25 inch coat ofmaterial was obtained around the carnation. The carnation was thencharged to a microwave oven. The coated carnation was then microwaved onthe HI setting for 4 minutes. After microwaving, the carnation wasdipped in the 40 weight percent slurry, producing a second 0.25 inchcoating, and microwaved for an additional 6 minutes. The carnation wasthen charged to a test kiln and fired to cone 9. The fired object ofthis example had a hollow interior, where the carnation had been burnedout.

Example 3

Replication of the Shape of a Flower

The procedure of Example 1 was repeated, with the exceptions a daisy wasused instead of a daffodil and the kiln drying procedure of the coateddaisy required some additional steps. The daisy was prepared in thefollowing manner. The stem of the daisy was cut off close to the head ofthe flower and placed face down on a block of wood and the back surfaceof the daisy was spray coated to a thickness of 0.0625 inches. The blockof wood with the daisy on it was charged to a 93 degree Celsius kiln for10 minutes and removed. The daisy was the turned over and spray coatedto a thickness of 0.0625 and placed into the kiln for 10 minutes. Thisprocedure was repeated until a coating thickness of 0.125 inches wasbuilt up on both front and back surfaces of the daisy. The coated daisywas charged to a kiln and fired in the same manner as in example 1.After the replicated object was removed from the kiln, it was coatedwith a clear glaze. Thereafter, the coated object was fired at cone 9.

Example 4

Replication of the Shape of a Burdock Bush

The procedure of Example 1 was repeated, with the exception that aburdock bush was used instead of a daffodil. Before spraying occurredthe burdock bush was cut into 6 inch lengths just below a break on thestem of the bushes. The 6 inch cut stems were tied together at the baseswith a piece of string. The surface coating and kiln firing procedure ofexample 1 was then used to finish the piece. After the replicatedburdock branches were removed from the kiln they were coated with aclear glaze. Thereafter, the burdock was then put into a test kiln andfired to cone 9.

Example 5

Replication of the Shape of a Flower

In the experiment of this Example, a rose which was obtained at theAlfred Greenhouse was coated with a specified mixture and then burnedout. This rose was approximately 2 inches in length after the stem wascut.

The mixture used to coat the rose was substantially identical to themixture used in Example 1.

The surfaces of the rose were then sprayed with the material in thespray gun until each of the surfaces was coated with material with athickness of about 0.0625 inches. The coated rose was then dried byplacing it into a kiln. The temperature of the kiln was 93 degreesCelsius, and the coated flower was maintained at this temperature for 10minutes.

The dried flower was then removed from the kiln, and another coat ofmaterial of about 0.0625 inches was sprayed onto it. Thereafter, theflower was then put back into the kiln, and the temperature of the kilnwas increased from 93 degrees Celsius to cone 9.

After cooling, the fired object, which replicated the shape of the rose,was then removed from the kiln.

Example 6

Heat Treated Cermet Electroplate

The ceramic gluten batch mixing procedure of example 1 was followed forthis example. In this example a 1 inch by 4 inch piece of galvanizedwindow screen obtained from Binghamton Hardware Co. Inc. 101 EldredgeStreet Box 927 Binghamton N.Y. 13902. was dipped in the ceramic glutenmixture. A coating of 0.25 inches thickness was obtained on the surfacesof the sheet metal. The coated piece of metal was charged to a test kilnand fired to a temperature of 950 degrees Celsius over a period of 3hours. After reaching a temperature of 950 degrees Celsius, the kiln wasturned off and allowed to cool to ambient. The coated screen was thenremoved from the kiln and placed into a salt bath mixture containing 80grams copper sulfate (obtained from the Fisher Scientific ChemicalManufacturing Division, Fairlawn N.J. 07410 catalog number C-490) whichwas diluted in 1000 grams of water. The anode of a battery charger wasconnected to a piece of copper. The cathode of the battery charger wasthen connected to the piece of coated metal. Both the copper and thecoated metal were then immersed in the prepared copper sulfate solution.The battery charger was turned on at the 6 volt setting and theelectroplating action was continued for 10 hours.

Example 7

Preparation of a Porous Filter Body

In substantial accordance with the procedure described in Example 1, andusing substantially the same ratios of materials, a ceramic mixture wasprepared which contained kaolin, silica, feldspar, soda ash, and gluten.However, instead of using 25 grams of the vital wheat gluten, and 20grams of such gluten were used.

80.5 grams of the ceramic mixture (dry weight) were mixed with 53 gramsof water and stirred for 3 minutes to produce a substantiallyhomogeneous slurry.

An "O-CELL-O" sponge, which was 2.5 inches wide by 4.25 inches long by0.5 inches thick, was cut into 1.4 inch segments. One segment of thesponge was then compressed and immersed into the slurry; while in theslurry, the compressive force on the sponge was released, therebysaturating the sponge with slurry.

The saturated sponge was then charged to a conventional microwave andsubjected to radiation at the high setting for three minutes; duringmicrowave treatment, the sample was rotated with a conventionalmechanical microwave rotisserie at a speed of about 6 revolutions perminute.

The microwaved sponge material was then charged to a gas-fired furnaceand heated to a temperature of 1170 degrees Celsius over a period of 12hours. Once the material had reached the 1170 degree Celsiustemperature, it was maintained at this temperature for 5 minutes.Thereafter, it was cooled to ambient over a period of 12 hours.

The fired body was sectioned. Visual observation indicated that,although it was light weight, it had a uniform, fine pore distribution.

Example 8

The procedure of Example 7 was substantially repeated, with theexception that the slurry was prepared by mixing 80.5 grams of theceramic mixture with 67 grams of water, and the saturated spongematerial was subjected to microwave radiation for 4.5 minutes at thehigh setting. The fired body of this example had greater porosity thanthe fired body of Example 7.

Example 8A

The procedure of Example 8 was substantially repeated, with theexception that the slurry was prepared by mixing 80.5 grams of theceramic mixture with 75 grams of water, and the saturated spongematerial was subjected to microwave radiation for 6.0 minutes at thehigh setting. The fired body of this example had greater porosity thanthe fired body of Example 8.

Example 9

Preparation of a Porous Filter Body

A ceramic mixture was prepared which contained 4,600 grams of "EPKkaolin," 3,400 grams of flint, 1,980 grams of feldspar, 120 grams ofsoda ash, and 50 grams of gluten; these reagents are described inExample 1.

The aforementioned materials were mixed and then comminuted for 12 hoursin "Roalox" 1 gallon mill jars (obtained from VWR Scientific, CN 1380,Piscataway, N.J., 08854, catalog number 48908-068) together with 4,053grams of "Burundum" aluminum oxide cylinders (obtained from VWRScientific, CN 1380, Piscataway, N.J., 08854, catalog number 48908-068)at a speed of 30 revolutions per minute. The mill jars were rotated on a"JOMAC" roller cleaner (obtained from Jomac, Inc., Warrington, Pa.,18976, Model TAB.)

The comminuted mixture was then mixed with 3,217 grams of distilledwater and stirred for 15 minutes to produce a substantially homogeneousmixture.

The homogeneous mixture was then extruded on a "System One" PowerExtruder (manufactured by the Bailey Equipment Corporation ofPennsylvania) into cylinders which had a one-inch diameter and were oneinch in length. These green bodies were then air dried for 12 hours andwere then charged to a gas fired furnace. The temperature of the furnacewas raised to cone nine and maintained at this temperature for fifteenminutes. Thereafter, the furnace was allowed to cool to ambienttemperature over a period of twenty-four hours.

The samples were tested for total porosity, total intrusion volume, andmedian pore diameter, using the mercury intrusion porosimetry techniquedescribed in the specification; the apparatus used was a MicromeriticsAutopore II 9220 instrument (manufactured by the MicromeriticsCorporation of 1 Micromeritics Drive, Norcross, Ga. 30093). The sampleshad an average total porosity of 7.8 percent, an average total intrusionvolume of 0.0304 milliliters per gram, and a median pore diameter of0.51 microns.

Comparative Example 10

The procedure of Example 9 was substantially repeated, with theexception that the gluten was omitted from the batch and 2,398 grams ofwater were used. The fired samples had an average total porosity of 4.9percent, an average total intrusion volume of 0.0209 milliliters pergram, and a median pore diameter of 0.32 microns.

Example 11

The procedure of Example 9 was substantially repeated, with theexception that, instead of 50 grams of gluten, 100 grams of gluten wereused and 4,790 grams of water were used. The samples had an averagetotal porosity of 8.9 percent, an average total intrusion volume of0.0392 milliliters per gram, and a median pore diameter of 0.71 microns.

Example 12

The procedure of Example 9 was substantially repeated, with theexception that, instead of 50 grams of gluten, 200 grams of gluten wereused and 4,060 grams of water were used. The samples had an averagetotal porosity of 9.2 percent, an average total intrusion volume of0.0408 milliliters per gram, and a median pore diameter of 0.66 microns.

Example 13

The procedure of Example 9 was substantially repeated, with theexception that, instead of 50 grams of gluten, 500 grams of gluten wereused and 6,394 grams of water were used. The samples had an averagetotal porosity of 13.2 percent, an average total intrusion volume of0.0603 milliliters per gram, and a median pore diameter of 1.46 microns.

Example 14

The procedure of Example 9 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1000 grams of gluten wereused and 5,716 grams of water were used. The samples had an averagetotal porosity of 14.3 percent, an average total intrusion volume of0.0665 milliliters per gram, and a median pore diameter of 1.6 microns.

Example 15

The procedure of Example 9 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1500 grams of gluten wereused and 6,766 grams of water were used. The samples had an averagetotal porosity of 16.1 percent, an average total intrusion volume of0.0766 milliliters per gram, and a median pore diameter of 2.48 microns.

Example 16

The procedure of Example 9 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2000 grams of gluten wereused and 7,782 grams of water were used. The samples had an averagetotal porosity of 17.2 percent, an average total intrusion volume of0.0844 milliliters per gram, and a median pore diameter of 3.9 microns.

Example 17

The procedure of Example 9 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2,500 grams of glutenwere used and 7,757 grams of water were used. The samples had an averagetotal porosity of 16.0 percent, and an average total intrusion volume of0.0787 milliliters per gram.

Example 18

The procedure of Example 9 was substantially followed, with theexception that the green bodies were fired to cone 7. The samples had anaverage total porosity of 24.3 percent, an average total intrusionvolume 0.1256 milliliters per gram, and a median pore diameter of 0.59microns.

Comparative Example 19

The procedure of Example 18 was substantially followed, with theexception that no gluten was used. The samples had an average totalporosity of 20.2 percent, an average total intrusion volume of 0.0977milliliters per gram, and a median pore diameter of 0.43 microns.

Example 20

The procedure of Example 18 was substantially repeated, with theexception that, instead of 50 grams of gluten, 100 grams of gluten wereused and 4,790 grams of water were used. The samples had an averagetotal porosity of 25.5 percent, an average total intrusion volume of0.1311 milliliters per gram, and a median pore diameter of 0.71 microns.

Example 21

The procedure of Example 18 was substantially repeated, with theexception that, instead of 50 grams of gluten, 200 grams of gluten wereused and 4,060 grams of water were used. The samples had an averagetotal porosity of 27.7 percent, an average total intrusion volume of0.1487 milliliters per gram, and a median pore diameter of 0.77 microns.

Example 22

The procedure of Example 18 was substantially repeated, with theexception that, instead of 50 grams of gluten, 500 grams of gluten wereused and 6,394 grams of water were used. The samples had an averagetotal porosity of 34.9 percent, an average total intrusion volume of0.2068 milliliters per gram, and a median pore diameter of 1.18 microns.

Example 23

The procedure of Example 18 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1000 grams of gluten wereused and 5,716 grams of water were used. The samples had an averagetotal porosity of 35.1 percent, an average total intrusion volume of0.2071 milliliters per gram, and a median pore diameter of 1.37 microns.

Example 24

The procedure of Example 18 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1500 grams of gluten wereused and 6,766 grams of water were used. The samples had an averagetotal porosity of 37.3 percent, an average total intrusion volume of0.2338 milliliters per gram, and a median pore diameter of 1.82 microns.

Example 25

The procedure of Example 18 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2000 grams of gluten wereused and 7,782 grams of water were used. The samples had an averagetotal porosity of 37.9 percent, an average total intrusion volume of0.2346 milliliters per gram, and a median pore diameter of 1.6 microns.

Example 26

The procedure of Example 18 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2,500 grams of glutenwere used and 7,757 grams of water were used. The samples had an averagetotal porosity of 41.1 percent, and an average total intrusion volume of0.2728 milliliters per gram, and a median pore diameter of 1.47 microns.

Example 27

The procedure of Example 9 was substantially followed with the exceptionthat, instead of air drying the green bodies, the green bodies weredried in an oven at a temperature of 80 degrees Celsius for 12 hours.The fired samples had an average total porosity of 8.65 percent, anaverage total intrusion volume of 0.0380 milliliters per gram, and amedian pore diameter of 0.9057 microns.

Comparative Example 28

The procedure of Example 27 was substantially repeated, with theexception that the gluten was omitted from the batch and 2,398 grams ofwater were used. The fired samples had an average total porosity of 5.42percent, an average total intrusion volume of 0.0249 milliliters pergram, and a median pore diameter of 0.4064 microns.

Example 29

The procedure of Example 27 was substantially repeated, with theexception that, instead of 50 grams of gluten, 100 grams of gluten wereused and 4,790 grams of water were used. The samples had an averagetotal porosity of 8.61 percent, an average total intrusion volume of0.0376 milliliters per gram, and a median pore diameter of 0.835microns.

Example 30

The procedure of Example 27 was substantially repeated, with theexception that, instead of 50 grams of gluten, 200 grams of gluten wereused and 4,060 grams of water were used. The samples had an averagetotal porosity of 10.7 percent, an average total intrusion volume of0.0480 milliliters per gram, and a median pore diameter of 1.19 microns.

Example 31

The procedure of Example 27 was substantially repeated, with theexception that, instead of 50 grams of gluten, 500 grams of gluten wereused and 6,394 grams of water were used. The samples had an averagetotal porosity of 12.1 percent, an average total intrusion volume of0.055 milliliters per gram, and a median pore diameter of 1.30 microns.

Example 31

The procedure of Example 27 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1000 grams of gluten wereused and 5,716 grams of water were used. The samples had an averagetotal porosity of 14.4 percent, an average total intrusion volume of0.0641 milliliters per gram, and a median pore diameter of 1.59 microns.

Example 32

The procedure of Example 27 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1500 grams of gluten wereused and 6,766 grams of water were used. The samples had an averagetotal porosity of 16.6 percent, an average total intrusion volume of0.0802 milliliters per gram, and a median pore diameter of 10.88microns.

Example 33

The procedure of Example 27 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2000 grams of gluten wereused and 7,782 grams of water were used. The samples had an averagetotal porosity of 17.0 percent, an average total intrusion volume of0.0849 milliliters per gram, and a median pore diameter of 35.96microns.

Example 34

The procedure of Example 27 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2,500 grams of glutenwere used and 7,757 grams of water were used. The samples had an averagetotal porosity of 20.7 percent, an average total intrusion volume of0.1073 milliliters per gram, and a median pore diameter of 52.79microns.

Example 35

The procedure of Example 27 was substantially followed, with theexception that the green bodies were fired to cone 7. The samples had anaverage total porosity of 25.3 percent, an average total intrusionvolume 0.130 milliliters per gram, and a median pore diameter of 0.73microns.

Comparative Example 36

The procedure of Example 35 was substantially followed, with theexception that no gluten used. The samples had an average total porosityof 22.3 percent, an average total intrusion volume of 0.1111 millilitersper gram, and a median pore diameter of 0.49 microns.

Example 37

The procedure of Example 35 was substantially repeated, with theexception that, instead of 50 grams of gluten, 100 grams of gluten wereused and 4,790 grams of water were used. The samples had an averagetotal porosity of 27.1 percent, an average total intrusion volume of0.1424 milliliters per gram, and a median pore diameter of 0.82 microns.

Example 38

The procedure of Example 35 was substantially repeated, with theexception that, instead of 50 grams of gluten, 200 grams of gluten wereused and 4,060 grams of water were used. The samples had an averagetotal porosity of 28.3 percent, an average total intrusion volume of0.1539 milliliters per gram, and a median pore diameter of 0.87 microns.

Example 39

The procedure of Example 35 was substantially repeated, with theexception that, instead of 50 grams of gluten, 500 grams of gluten wereused and 6,394 grams of water were used. The samples had an averagetotal porosity of 31.4 percent, an average total intrusion volume of0.1774 milliliters per gram, and a median pore diameter of 1.09 microns.

Example 40

The procedure of Example 35 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1000 grams of gluten wereused and 5,716 grams of water were used. The samples had an averagetotal porosity of 34.6 percent, an average total intrusion volume of0.2040 milliliters per gram, and a median pore diameter of 1.27 microns.

Example 41

The procedure of Example 35 was substantially repeated, with theexception that, instead of 50 grams of gluten, 1500 grams of gluten wereused and 6,766 grams of water were used. The samples had an averagetotal porosity of 37.1 percent, an average total intrusion volume of0.2274 milliliters per gram, and a median pore diameter of 1.37 microns.

Example 42

The procedure of Example 35 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2000 grams of gluten wereused and 7,782 grams of water were used. The samples had an averagetotal porosity of 36.9 percent, an average total intrusion volume of0.2389 milliliters per gram, and a median pore diameter of 1.28 microns.

Example 43

The procedure of Example 35 was substantially repeated, with theexception that, instead of 50 grams of gluten, 2,500 grams of glutenwere used and 7,757 grams of water were used. The samples had an averagetotal porosity of 42.8 percent, and an average total intrusion volume of0.2991 milliliters per gram, and a median pore diameter of 1.78 microns.

Examples 44-78

Preparation of Polymer/Ceramic Composites

The procedures described in Examples 9 through 43 were substantiallyrepeated, with the exception that the fired samples were thereaftertreated to prepare polymer/ceramic composite materials by vacuumimpregnation with an epoxy resin.

The epoxy resin used in these experiments was a low viscosity four-partepoxy which was purchased from the Ernest F. Fullam Inc. of 900 AlbanyShaker Road, Latham, N.Y. This resin was prepared by mixing 10 grams of"VCD" (ERL4206 vinylcyclohexane dioxide resin), 6 grams of DER736 resin,26 grams NSA (dodecenyl succinic anhydride), and 0.4 grams of DMAE(Dimethylaminoethanol) in a paper cup and stirring the mixture with astick for three minutes. Thereafter, the porous ceramic body was placedin the vacuum chamber of a vacuum impregnation unit (available fromBuehler LTD Lake Bluff, Ill. 60044), immersed in the epoxy mixture andheld in the vacuum chamber which operated at 30 inches of mercury for 90minutes.

Each of the impregnated porous ceramic body was then removed from thevacuum chamber and allowed to cure in a 70 degree Celsius oven for aperiod of twelve hours. Thereafter the impregnated body was polishedusing an ECOMET 3 Variable Speed Grinder-Polisher with an AUTOMET 2Power Head (available from Buehler LTD Lake Bluff, Ill. 60044).Polishing included sequentially reducing the polish grind media from 45micron pad then with diamond grit 15 micron, 6 micron, 1 micron and thena final polishing with submicron colloidal solution. The samples werepolished for 10 minutes with each pad starting with the 45 micron padand ending with the submicron colloidal silica solution.

Each of the polished samples were then subjected to scanning electronmicroscopic analysis. This analysis indicated that the samples weresubstantially impregnated with epoxy uniformly throughout the fine poredistribution of the sample.

Example 79

Preparation of a Ceramic Moisture Sensors

The procedures described in Examples 9-17 were substantially repeated toform a series of cylindrical ceramic moisture sensors.

The ceramic moisture sensors were manufactured by extruding ahomogeneous mixture of each mixture described in Examples 9 through 17into a series of both one inch diameter one inch long cylinders, andthree quarter inch diameter and three quarter inch long cylinders. Thesecylinders were allowed to air dry for 12 hours.

The air dried 1 inch cylinder centers where drilled out with a threequarter inch drill bit to a depth of three quarters of an inch.

The air dried three quarter inch cylinder centers where drilled out witha one half inch drill bit to a depth of one half inch.

The samples where then fired in accordance with the firing proceduredescribed in Example 9. The sensors were assembled with three quarterinch cylinders of stainless steel 24×24 mesh screen, with a wire size of0.0075 inches, (available from Metals Inc. at 26225 Broadway Road,Clevland Ohio 44146), inserted into the drilled ceramic pieces. Thesmaller ceramic cylinder and mesh were inserted into the center of the 1inch ceramic cylinder.

Wires were soldered to the stainless steel mesh to provide anode cathodeconnection terminals.

Example 80

In substantial accordance of the procedure of Examples 9-17, a series ofceramic fishing lures were prepared by extruding a homogeneous mixtureof each mixture described in Examples 9 through 17 into one quarter inchdiameter one inch long cylinders which where allowed to air dry for 12hours.

The samples where then fired in accordance with the firing procedure inExample 9. After such firing the porous ceramic cylinders were epoxieds,using EPOXI-PATCH (available from the Dexter Corporation in Olean, N.Y.14760), to a fishing hook and allowed to cure for 12 hours. The epoxiedcylinder and hook where inserted into a rubber worm.

It is to be understood that the aforementioned description isillustrative only and that changes can be made in the apparatus, in theingredients and their proportions, and in the sequence of combinationsand process steps, as well as in other aspects of the inventiondiscussed herein, without departing from the scope of the invention asdefined in the following claims.

We claim:
 1. A process for preparing a ceramic body, comprising thesteps of sequentially:(a) mixing at least about 40 weight percent ofceramic material (by total weight of said ceramic material and gluten,less than about 60 weight percent of said gluten (by total weight ofsaid ceramic material and said gluten), and from about 20 to about 80weight percent of water (by total weight of said ceramic material, saidgluten, and said water) to produce a mixture, wherein:1. at least about90 weight percent of the particles of said ceramic material are smallerthan about 20 microns, and at least about 50 weight percent of theparticles of said ceramic material are from about 0.5 to about 2microns, and
 2. said mixture has a pH of from about 2 to about 8; (b)forming said mixture into a green body; and (c) firing said green bodyuntil a body which contains substantially none of said gluten isproduced.
 2. The process as recited in claim 1, wherein said mixture hasa pH of from about 6.5 to about 7.5.
 3. The process as recited in claim1, wherein said mixture is comprised of from about 30 to about 70 weightpercent of said water (by total weight of said ceramic material, saidgluten, and said water).
 4. The process as recited in claim 1, whereinsaid mixture is comprised of from about 45 to about 75 weight percent ofsaid water (by total weight of said ceramic material, said gluten, andsaid water).
 5. The process as recited in claim 1, wherein said greenbody is fired while disposed within a microwave oven.
 6. The process asrecited in claim 1, wherein said green body is fired until it has adensity which is at least about 95 percent of its theoretical density.